Osseous Genioplasty: Prevention of Witch's Chin Deformity with Custom-Milled Plates
Alex G. Lambi, MD, PhD1, Rosemarie Byrd, BS2, Connor Bradley, BS2, Ellie Volpicelli, BS2, James P. Bradley, MD2.
1UCLA Health, Los Angeles, CA, USA, 2Temple University School of Medicine, Philadelphia, PA, USA.
PURPOSE: Osseous genioplasty is a powerful surgical procedure that can correct chin dysmorphology with movements in 6 directions (sagitally, vertically, and horizontally). However, the technique may result in the untoward soft tissue sequellae of "Witch's chin" deformity or chin ptosis. Virtual surgical planning for orthognathic cases or osseous genioplasty allows for precise cutting guides and custom-plate manufacturing and for the use of a no-degloving 90-degree plate with lag screw method. We compared the clinical outcomes of the traditional (stair-step plate) method to this new technique for special emphasis on chin ptosis.
METHODS: Patients who underwent osseous genioplasty were randomized for 1) traditional (stair-step plate) method or 2) new no-degloving and studied prospectively (n=76). We recorded degree of advancement, complications, direct and photographic measurements for chin ptosis, and lateral cephalogram analysis. In addition, Face-Q chin assessment was used for patient reported outcomes.
RESULTS: Both comparative groups had similar age, comorbidities, osseous advancement (5.8cm vs 5.6cm), vertical lengthening (2.5cm vs 2.6cm), and a similar complication profile (plate exposure, prolonged paresthesias) except for soft tissue ptosis. Chin ptosis was seen more often with traditional vs no-degloving procedure: lateral image measurements (38% vs 4%), lateral cephalogram (41% vs 9%). In addition, greater satisfaction was seen with Chin Face-Q for no degloving = 92.9+19 vs traditional = 83.1+15.
CONCLUSION: The no degloving, pre-milled plate osseous genioplasty was superior to the traditional method with regard to chin ptosis and prevention of "Witch's chin" deformity.
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